Emergency traffic control system



June 21, 1966 P. c. CAMPANA ETAL 3,257,641

EMERGENCY TRAFFIC CONTROL SYSTEM 4; Sheets-Sheet 1 Filed May 31, 1963 STEADY RED EME RGEN CY VEHI,CLE

STEADY RED SIGNAL OPERATING NORMALLY RECEIVER EMERGENCY LIGHT INVENTORS C. CAMPANA 8 w w I52 I56 I53 57 BY THOMASTCHRYSLER .7 .7 FIG 4 ATTORNEYS June 1966 P. c. CAMPANA ETAL 3,257,641

EMERGENCY TRAFFIC CONTROL SYSTEM Filed May 31, 1963 4 Sheets-Sneet 2 -o 0- g 4 U A? Q EB A INVENTORS.

PATSY C. CAMPANA 8| BY THOMAS T. CHRYSLER ATTORNEYS June 21, 1966 Filed May 31, 1963 P. c. CAMPANA ETAL 3,257,641

EMERGENCY TRAFFIC CONTROL SYSTEM 4 Sheets-Sneet 5 nov A c. EMERGENCY CIRCUIT IOO RELAY I "-1 HO SIREN OR BELL i ")4 WP EMERGENCY uem' 92 l RED fl": RED I I09 02 93 I 92 FIG. 6 M I 93L: 96 la A Ii II III A INVENTORS. PATSY C. CAMPANA 8 BY THOMAS T. CHRYSLER jqyaya y ATTORNEYS June 21, 1966 P. c. CAMPANA ETAL 3,257,641

EMERGENCY TRAFFIC CONTROL SYSTEM 4 Sheets-Sneet 4 Filed May 31, 1963 w QE INVENTORS. PATSY C. CAMPANA 8 THOMAS T. CHRYSLER i P m mw ET: 3: QN h:

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ATTOR NEYS United States Patent I O 3,257,641 EMERGENCY TRAFFIC coNrRoL SYSTEM Patsy C. Campana and Thomas T. Chrysler, Lorain, Ohio,

This invention relates to a remote control system, and is more particularly directed to an emergency traffic system which may be controlled from a moving vehicle, or vehicles.

With the advent of cities of increasing size, it has become necessary to install trafiic signals which will insure the smooth and continuous flow of traffic throughout parts of the city or town. While this serves the public in good stead during normal traffic movements, considerable difficulty is encountered when an emergency vehicle, such as an ambulance, police squad car, fire fighting equipment, and the like, findit necessary to move from one place to the other at high rates of speed in order to respond to emergency calls.

In its broadest sense, the present invention envisions a means carried by the mobile vehicle which, when properly actuated, will serve to halt the flow of trafiic, without interrupting the normal sequence or timing of the trafiic lights. As pointed out above, the smooth flow of traffic is enhanced by the use of signals making the presence of such necessary for good traific control. Each of the signals is sequentially timed in relation to the other in such a manner that a vehicle travelling at a set Speed, normally within the speed limit, may move through a series of signals without requiring it to stop. .The arrangement and setting of the sequence of traflic signals require extensive surveys and studies and when the timing relationship between lights is once set, it is most desirable if it is not interrupted.

In the past, remote control emergency traflic systems have been proposed; however, have not been entirely satisfactory for one reason or another. Systems which relied upon an audible signal, such as a siren or born to control the traffic lights at an intersection by turning all the lights red, have their deficiencies. Among these, the sound could be blocked by a vehicle or other obstruction between the emergency vehicle and the receiver at the intersection. Further problems have been encounteredin finding a system which would be economically feasible to install, but yet virtually foolproof in its operation. Still further, it is essential from the commercial aspects of such a system that it be readily installed in existing traffic systems with a minimum amount of effort and skill required.

Other systems operated on a high frequency band, well outside the citizens band, so that it was necessary to be licensed by the Federal Communications Commisison. Other deficiencies which have been noted are that some systems relied on a feed and time relationship of the pulse in order to prevent unauthorized use of such systems. Still others did not utilize a receiver requiring a perfect pulse and consequently, aircraft transmitting jamming signals over a broad band would cause actuation of the lights. Other systems, which were more complex, relied on diverse signals for traffic patterns at right angles to each other. However, a problem is presented by the diagonal streets in an embodiment such as this. Further 3,257,641 Patented June 21, 1966 problems have been encountered because the emergency control system interrupts the normal timing sequence of the traffic control system, requiring the laborious and time consuming task of re-timing the series of lights after use.

The present system is directed towards an economical package unit which may be readily installed in an existing trafiic control box or in a weather proof container adjacent to the traflic control box. The receiver has built in adjustments which enable it to be connected in the existing trafiic system in several different ways such that the code requirement of the state may be readily met, without any change whatsoever in the receiver. For example, if the state code or city ordinance requires an amber light for a short duration before the red may come on, the instant system is entirely flexible, enabling it to be wired into an existing system without requiring change in the receiver, and only relatively minor changes in the wiring of the existing system being necessary.

Another important aspect of the instant unit is the ability of it to operate for any selected period without interruption of the normal timing of the lights. A short time after the emergency vehicle has passed, the traffic signals will resume their normal sequence of operation.

The present invention utilizes a selective filter circuit which requires a substantially perfect pulse in order to actuate the traflic signals, thereby preventing the unauthorized use of the signals. To the attainment of this end, a transformer couples the amplifer to the selective filter circuit which in turn controls the bias on the relay actuating means. Intermediate the transformer and thyratron is a wave trap having an adjustable choke which allows adjustment and maximizes the sensitivity of the filter circuit.

As will become apparent, on reception of the proper signal from the transmitter through the antenna and amplifier, the proper signal will be detected first through the amplifier, and passed by the filter into a voltage and time switching arrangement to energize the relay actuating means, which in one embodiment is a thyratron. Upon triggering the relay actuating means, the main control relay closes, deenergizing the sequentially operated control system while energizing the emergency system to turn the lights red in all directions. As pointed out previously, the receiver may be wired in the existing circuit so as to provide for a short interval of amber before going red, if desired, or, alternatively, may be wired in other manners to give various combinatons of red and green, as will be more clearly apparent.

Suitable means may be provided to alert other emergency vehicles which are proceeding to the scene, that the light at the intersection is under the control of a previous emergency vehicle, thereby requiring the second emergency vehicle to exercise caution in approaching the intersection.

Substantial benefits are obtained by the use of the instant device. First and foremost is the ability of the emergency vehicle to get to the scene of the emergency in about 40% less time than is normally required. In cases of personal injuries, fires and emergencies of this nature, requiring immediate attention, the precious minutes saved often determine success or failure in achieving the objectives of the emergency call Moreover, it provides means whereby the emergency vehicle may proceed at a higher rate of speed with greater safety than was possible in the past when reliance was placed upon a vehicle flashing red light and/or siren. A reduction in insurance costs is obtainable for those residents in a community utilizing such a system. Obviously, these are but a few of the important advantages obtained with the present system and further advantages and benefits will become apparent hereinafter.

It is therefore an object of this invention to provide a traffic light control system which enables an emergency vehicle answering an emergency call to selectively control the traffic lights at any corner along the artery used.

It is a further object of this invention to provide a traflic control system which will include a receiver means employing a selective filter so that only authorized personnel will be able to utilize the system.

It is a further object of this invention to provide a traific light control system which will allow the emergency vehicle to control the traflic lights at the intersection without interrupting the time sequence between the respective lights so interrupted.

It is a further object of this invention to provide a traflic control system which due to the construction of the receiver circuit may be readily incorporated in existing systems with a minimum of change and effort.

It is a further object of this invention to provide a traflic light control system which will permit various signal arrangements to be had with relatively minor changes in the existing system.

Further and fuller objects will become readily apparent upon consideration of the following detailed description, especially when taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a plan view of a series of intersections on a reduced scale to show the application of the invention;

FIG. 2 is a perspective view of a traffic signal having a receiver mounted thereon;

FIG. 3 is a schematic circuit diagram of the receiver unit used in the instant invention;

FIG. 4 is a modified form of actuator and filter section which may be used in lieu of that shown in the right-hand portion of FIG. 3;

FIG. 5 is a schematic view of a portable transmitter to be used with the receiver shown;

FIG. 6 is a wiring diagram of a signal control system' illustrating the emergency circuit in conjunction therewith;

FIG. 7 is a schematic diagram of a conventional trafiic signal illustrating a modified form of wiring diagram for the lights to be actuated to red in all directions after a short period of amber; and

FIG. 8 is a wiring diagram similar to FIGS. 5 and 6, however, illustrating the wiring diagram for the signals to be red for cross trafiic and green for main traffic after a short period of amber.

, Referring now to FIG. 1, a plan view of a main street 10 having cross streets 11, 12 and 13 is illustrated with the reds and greens being shown in a conventional manner. The traflic intersection 14 is illustrated with the signal operating normally, the emergency vehicle 15 having passed that intersection. Intersection formed by main street 10 and cross street 12 is shown as having steady red in all four directions. Similarly, the intersection formed by main street 10 and cross street 13 is illustrated as showing steady red in all four directions, preparing the intersection for the crossing of the emergency vehicle 15 which is travelling in the directions of the arrows 16. This mode of opertaion is made possible by traflic lights which are positioned centrally of the intersection or on the four corners thereof. Such traflic control signals are similar to the one shown in FIG. 2. The actuating receiver is illustrated at 17 as being disposed on the top of the light, however, it may be enclosed in the usual trafiic control box with an outside antenna, or on a pole adjacent the traflic box, since it is contemplated that a weather proof container may be provided, depending upon the particular wants and desires of the purchaser of the system.

The tratfic light shown in FIG. 2 at 18 has the normal red, amber and green signals. Additionally, an emergency light 19 may be disposed thereunder to illustrate a flashing red once the signal is under the control of an emergency vehicle to alert subsequent emergency vehicles approaching the intersection. Similarly, a siren or bell 20 may be energized for the duration that the control of the signal is removed from the control of normal sequentially controlled mechanism. The flashing red light or siren are only exemplary of the possible alternatives which may be used.

The function and advantages of the present system will be appreciated upon description of the means provided to achieve the objects noted. The receiver shown in FIG. 3 is provided with a power supply transformer 34 which is connected to suitable volt source having a fuse or circuit breaker in one side of the line. The secondary of the transformer provides a 6.3 voltage source for the filaments indicated generally at 35. The heater 36 in the filament 35 is provided for the tube, the dual triode indicated at 47 and 47'. The other portion of the secondary of the transformer 34 has a surge current limiting resistor 87 in series with a silicon rectifier 86, which rectifies the 110 volt secondary into pure direct current voltage. The resistor 88 and capacitors 39 and 39 complete the combination to apply the B+ voltage to the plates of the tubes.

An antenna 30 which may be cut to appropriate lengths for the preferred 255 megacycle band is connected through capacitor 32 to the center of coil 33 in the cathode of the tube 31, The resistor 41 and capacitor 42 are serially connected with the coil 33 to the common and B+ voltage side of the transformer 34, respectively. A transformer 37 has its primary serially connected in the plate circuit of the tube 31 with the secondary of the transformer being center tapped to obtain the proper operating frequency. An adjustable slug indicated by the conventional arrow allows tuning to the proper operating frequency thereby imposing the altrenating RF signal voltage to be impressed on the input of one half the triode. The resistor and capacitor 41 and 42 in parallel provide the necessary bias voltage to the tube 31 for the proper RF amplification. A conventional type decoupling circuit including a resistor and capacitor, connected as indicated, forms the plate decoupling circuit of the vacuum tube 31, through the primary of the RF transformer 37.

The secondary of the transformer 37 is hooked in the plate and grid circuit of the first half of the triode 47 intermediate the secondary of the transformer and the grid to provide the necessary operating grid voltage to detect the RF signal. The center tap on the transformer 37 lead through a coil 43 to isolate the RF voltage. The audio frequency tone is coupled to the grid of the other half of the triode indicated at 47' through coupling capacitor 45, with the second half of the triode 47' operating as an audio amplifier. A plate decoupling circuit 44, similar to that shown at 38, is provided with the capacitor of the coupling circuit connected to the common side and the resistor connected to the 13+ side of the secondary of the transformer 34. The decoupling circuit 44 provides the plate output load circuit for the one half of the triode shown at 47.

A resistor 46 is connected to the grid of the other half of the triode indicated at 47 into the common side of the transformer 34. Resistor connects the cathode to the common side 171 of the secondary of the transformer 34. The plate of the audio amplifier 47 is tapped through line 48 through resistor 172 to the B+ side of the power supply, which provides the plate circuit 48 with the necessary load. The output of the audio amplifier 47 couples the audio voltage output to the grid of the tube 52, through a capacitor 49 and a variable resistor 50. The resistor 50 has a center tap to completethe circuit, with the center tap lead to the grid 51. Resistor 50 provides a simple, but efllcient method and means of adjusting the gain to insure the desired audio voltage on the control grid 51 of the tube 52. The cathode 80 of the tube 52 is connected to the suppresser grid 81 with both being connected to the ground or the common side of the power supply through capacitor 173 and resistor 174 in parallel to provide the necessary bias voltage for the proper audio voltage operation of the tube 52. The screen grid is connected to the secondary of the power supply transformer 34 through capacitor 175 and resistor 176, the latter being connected to the B+ side with the former being connected to the common side to provide the necessary DC. voltage for the screen grid. The plate 177 of the tube 52 is fed through the primary of an audio transformer 53 back to the B+ voltage supply.

A response to a 1500 or similar cycle signal is tuned by the wave trap 63, having adjustable coil 62 and capacitor 64 in parallel. Silicon rectifiers 61 and 61' are connected to the secondary of the transformer 53 to rectify the alternating output to a pure DC. voltage. A voltage dividing network 59 and 60 is coupled to the rectifiers 61 and 61. Capacitors 56, 57 and 58 act as stabilizing capacitors in the filter circuit 54. Resistors 178 and 179 form additional filtering and stabilizing network in the grid circuit of the thyratron 67. Resistor 65 coupled between the secondary of the transformer 53 and through the wave trap, as well as being connected to the center junction of the voltage dividing network formed by the resistors 59 and 60. The thyratron 67 has a cathode connected to the 6.3 supply, as well as grid 179. The plate of the thyratron 67 is lead through a relay 68 which may or may not be adjustable. In parallel with the relay a stabilizing capacitor 69 is provided with resistor 70 back to the 110 volt secondary of the transformer 34. Capacitors 55, 58 and 69 provide a stabilizing condition in the grid control circuit of the thyratron 67, giving a positive performance to the relay 68, eliminating any tendency to chatter which would occur absent the stabilizing influence of the capacitors shown or a suitable equivalent.

Referring now to FIG. 4, a fragmentary portion of a modified form of filter and actuator circuit is shown. It is intended that the terminals XY will be connected to the terminals X'Y of FIG. 3, with the circuit to the right of the X'Y being removed and the circuit shown in FIG- 4 being substituted in lieu thereof. The circuit in FIG. 4 is illustrative of the possibilities of transistorizing the complete receiver circuit in order to reduce the size and eX- pense of the units.

The selective filter circuit 150 is connected to the secondary of the audio transformer 53, as was true in the vacuum tube circuit ofFIG. 3. A series of resistors 151, 152, 153 and 154 serve to reduce the voltage from approximately 120 volts at terminal Y in successive steps to 37, 27 and 25 volts at each of the terminals 155, 156 and 157. The branch olf terminal 155 leads to a 33K resistor 158 to the filter circuit 150. The value and placement components in the filter circuit are identical to the components described in connection with FIG. 3. The thyratron shown in FIG. 3 to trigger the relay mechanism has been replaced by the circuit including the compound connected transistors 159 and 160. Compound connected transistors are particularly suited for the immediate application because of their high current amplification factor. Capacitor 161 connects the emitter of the transistor 159 to the collectors of each of the transistors, with all being coupled to ground terminal 162. Upon reception of the signal the bias on the base of transistor 159 becomes negative, allowing current to how, thus changing the bias on the base of transistor 160, which passes current through the relay 68, causing it to actuate closing contacts 71 and 72. A two meghom variable resistor 163 is connected to terminal 156 and together with a 120 kilohm resistor 164 permits sensitivity adjustment of the system. It can be appreciated that the use of solid state devices insures greater maintenance free life of the unit, while severely reducing the cost of manufacture. This construction is exemplary of one method of performing this function. The circuit in FIG. 4 illustrates that transistorization of the entire unit would be feasible as long as the intended function could be achieved.

The various components employed in the illustrative receiver and control apparatus shown in the figures submitted herewith may be varied considerably in accordance with the taste of the particular designer. The following table of component values has been found to be highly satisfactory in practice and is given herein as typical. It should be understood, however, that the following table of values is merely illustrative.

TABLE Component: Value 31 6AB4, triode. 47 12AT7, dual triode. 52 Gaug, tetrode. 67 2D21, thyratron, pento. 61 H 1N2859, sil. rect., 5 a., 150 piv. 61 IN2859, sil. rect., 5 a., 150 piv. 86 IN2863, sil. rect., 5 a., 500 piv. 32 47 mmfd, ceramic, 250 v. 42 .002, ceramic, 250 v. 38 .01, ceramic, 250 v. 44 .015, ceramic, 250 v. 200 47 mmfd, ceramic, 250 v. 45 .002, ceramic, 250 v. 49 c- .002, ceramic, 250 v. 173 3 section, 40 mfd., 150 v. 175 .01, ceramic, 250 v. 64 500 mmfd., ceramic, 250 v. '56 .01, ceramic, 250 v. 57 .01, ceramic, 250 v. 58 .47 mfd., paper, 50 v. 69 40 mfd., electro, 50 v. 39 3 section, 40 mfd., 150 v. 39' 3 section, 40 mfd., 150 V. 55 500 mfd. 33 2 turns, /2 dia., tap, 1 turn. 37 RF, slug, tuned to L freq. 53 Audio, Raeco, 969. 12 Slug tuned for 1500. 34 PWR, v., Sec. 6.3 v., Sec.

110 v., 15 watt. 6% Sigma, 9000, DC. resist. 41 180, /2 watt. 38 10K, /2 watt. 43 .47, radio freq. choke. 44 47K, /2 watt. 201 1 meg, /2 watt. 170 1K, /2 watt. 46 500K, potentiometer. 172 220K, /2 watt. 1 50 470K, /2 watt. 174 180, /2 watt. 176 10K, /2 watt. 60 470K, /2 Watt. 59 470K, /2 watt. 178 470K, /2 watt. 179 2-.2 meg, /2 watt.

88 1K, /2 watt. 87 22, /2 watt. 65 100K.

158 33K. 159 GT 81. 161 50 microfarad. GT 81.

163 2 meg.

7 TABLEContinued Component: Value 151 10K. 152 1K 153 270 154 3.3K

One form of transmitter which in the instant case is portable, used in conjunction with the receiver in FIGS. 3 and 4, is illustrated schematically in FIG. 5. A single tube transmitter has good enough gain to send the requisite signal for distances up to 2000 feet, which is gen erally more than enough distance for normal use. The transmitter has a conventional A and B power supplies indicated at 150 and 151, respectively. A suitable toggle switch 152 is provided in the power supply line providing the B+ voltage for the self-excited grid modulated oscillator 156. A resistor 153 and capacitor 154 are wired .in parallel. across the toggle switch 152. Battery 150 has its negative side connected through a push-button switch 155, which is in the filament circuit of tube 156. The push-button engages the contacts for approximately second energizing the battery 150 supplying filament voltage for the tube 156. The filament circuit through the tube 156 is completed with a ballast resistor 157 to maintain proper current in the tube 156. A coupling transformer 159 has the secondary 160 in parallel with the capacitor 158 and is serially connected with the resistor 161 to the grid of the tube 156. The transformer has an adjustable slug to obtain the desired audio modulated tone on the output RF signal. Capacitor 158 across secondary 160 completes the tuning adjustment for the desired tone. The primary of the transformer 159 is connected through-the positive side of the toggle switch 152 and serially connected with RF isolation resistor 162 to a center tap on coil 163. Coil 163 is indicated as having adjustable slug to adjust the inductance thereby to tune transmitter to the proper frequency, which in the present case is perferably 255 megacycles. One side of the coil 163 is coupled to the grid circuit through capacitor 164 to supply feed back from grid to plate to sustain oscillation. Coil 163 is coupled to the antenna through RF coupling capacitor 165 which has the opposite side thereof connected to the antenna, the latter being connected to the negative side of the B battery 151 and the positive side of the A battery 150 to complete the circuit. A list of the parts which may be used in this type of transmitter is provided below, however, any suitable substitute may be made without departing from the scope of this invention. It is to be understood that the use of transistors or solid state devices in the transmitter are contemplated, but in the interest of brevity, are not herein described.

PARTS LIST Resistor 157, .47 ohm, one watt carbon resistor.

Capacitor 158, 5,000 microfarad mica capacitor.

Audio transformer 159, slug tuned to approximately .1500

cycles.

Resistor 161, 47 kilohm, /2 watt carbon.

Resistor 162, 22 ohm, 2 watt carbon resistor.

Coil 163, three turn CT slug tuned to 255 megacycles.

Capacitors 164 and 165, 47 mmfd. capacitors.

It is apparent that the transmitter will occupy a minimum amount of space, approximately by 3" and about 1 /2" thick, making it conveniently carried. The coil 163 is tuned to 255 megacycles, whereas the coil 159 is tuned to 1500 cycles. In operation, upon actuation of the push-button 155, a signal is sent out over the antenna of the transmitter to the receiver with the operation hereinbefore described taking place. The few number of parts required in a transmitter allow it to be manufactured at minimal cost. The push-button used is engaged for only approximately a tenth of a second or less, thereby requiring low power drain on the batteries. The maximum range of the transmitter is 2,000 feet, with the sensitivity adjustable for lesser distance. It is to be understood that more than one set of tones could be incorporated in the transmitter and receiver to create more functions such as controlling cross or main traflic, or traffic at special intersections. The selectivity of such would enable the operator of an emergency vehicle to energize the appropriate switch for the respective tone to operate the lights in the manner he chooses.

It is possible to utilize a stationary transmitter to be affixed to the carrying vehicle which would utilize the low voltage power supply of the vehicle. Such is not described herein, in the interest of brevity.

Referring now to FIG. '6, a conventional form of wiring diagram for signal system is shown, with the novel emergency section connected thereto. The conventional system would include main power lines and 91. Connected across the lines 90 and 91 are series of lights 92, 96 and 94 which are controlled by a sequence means 95 which opens and closes the contacts 93 to sequentially time the lights. The line 90 includes normally closed contact 97, which provides continuous power to the lights under normal circumstances. The present emergency circuit envisions the use of a separate power line 98 to be used with the common line 91 of the normal supply. The line 98 is provided with a fuse, circuit breaker, or the like, indicated at 99. Across lines 91 and 98 is connected the terminals 73 and 74 of the receiver of FIGS. 3 or 4 in series with a relay 100. The relay 100 controls the normally closed contact 97, as well as normally open contact 101, which is in a circuit in parallel with the relay 100. Upon the signal being received by the receiver, the actuation of the relay 68, contacts 71 and 72 close, energizing relay 100. Relay 100 disconnects line 90, while closing contacts 101, 102 and 103. Contacts 102 and 103 by-pass the sequential switch 93, thereby energizing the amber lights. Switch 101 energizes a timing relay 104, as well as a relay 105 in parallel therewith. Relay 104 is a time delay relay which times zero to 10 seconds after power is applied before actuation thereof. While relay 104 is timing to come in, relay 105, being instantaneous and wired in parallel with relay 104, has been energized, closing contacts 107 and 108, to the red lights 92. Upon relay 104 completing its timed cycle, and then being energized, contact 106 closes completing the cicruit through the red lights 92. Simultaneously therewith, normally closed contact 109 in the amber light circuit opens, deenergizing the amber lights which were energized by relay 100 closing contacts 102 and 103. The main control relay 68 may be timed for any period from zero to 60 seconds, with the adjustment being provided in the receiver, and upon completing its timed cycle, falls open deenergizing the entire emergency system. The sequence means having run throughout the course of the emergency use picks up at the exact position it would have been if the emergency circuit had not been energized. It is to be noted that a siren or bell 110 and light 111 may be wired in parallel with the timing relay 104 and relay 105, as a warning to subsequent emergency vehicles that the intersection is under the control of a prior emergency vehicles, so that the second vehicle will proceed with caution through the intersection.

Referring now to FIG. 7, a modified form of wiring diagram is shown including the emergency system. The embodiment illustrated is shown as being wired for the lights to be red in all directions, after a brief period of amber. The present system again requires the use of only a single relay 68 in the receiver, which does not need to be a timing relay, as was true in the FIG. 6 embodiment. The relay 68 in the present case is an instantaneous relay energizing on reception of the transmitted signal and immediately fall-ing out thereafter. Timing relay 211 is energized and times while power is off since the contacts 71 and 72 controlled by relay 68 open cutting out the power to relay 211. Upon energization of the relay 68, contacts '71 and 72 close, energizing timing relay 211, between common line 112 and emergency line 113. Relay 211 closes contact 210 in the second relay circuit, energizing relays 116 and 117. Relay 117 opens contact 114 in the normal service line 115, cutting 011 power in the hot side of the line between the timing drum and the lights. Relay 116 is a timing relay which may be set to operate zero to 10 seconds after power is applied. Relay 116, after completing the timed cycle, actuates closing contacts 118 and 119. Relay 117, being instantaneously operable, has closed contacts 121) and 121 leading to the red lights in the cross and main, as well as 122 and 123 leading to the amber lights. Contact 118 being Open while relay 116 is timing to come in, prevents the red lights from coming on. The amber lights will be instantaneously energized, and remain energized until relay 116 completes its timed cycle and actuates. Relay 116, upon actuation, serves to open the contacts 119, and simultaneously therewith closes contacts 118, energizing the red lights in the main and cross directions. With the closing of contacts 210, the bell or siren, indicated at 124 with the light 125 wired in parallel, are energized to alert other emergency vehicles that the intersection is under the control of a previous emergency vehicle.

Relay 211, being timed for any period from zero to two minutes, keeps contacts 210 closed for the set period, thereby holding relays 116 and 117 in, keeping contacts 118, 121 and 121 closed, with the red lights thereby energized for the set period. Upon relay 211 completing the timed cycle, it deenergizes, opening contacts 210, thus cutting power to relay 116 and 117. When relay 117 is deenergized, contacts 114 in the hot side of the line 115 close allowing the sequence drum to resume its operation at the normal timed sequence it would have been in absent the use of the emergency circuit.

FIG. 8 illustrates an alternative method of connecting the emergency circuit to an existing control system. The existing control system includes lines 130 and 131. A series of lights are wired parallel across the line as shown. The emergency system may be applied by the addition of a separate line 132 connected to a suitable power source such that lines 131 and 132 will provide a 110 volt potential therebetween. A portion of the control circuit of FIG. 3 is shown with the connections 73 and 74, contacts 71 and 72 being serially connected with the relay 133 across the lines 131 and 132. Upon energization of 68, contacts 71 and 72 close completing the circuit through relay 133.

The energization of relay 133 serves to simultaneously close contacts 134 and 142, while opening normally closed contacts 144 in the hot side of the line. The opening of contacts 144 serves to remove control of the lights from the sequence control means. The closing of contacts 134'completes the circuit through relays 135 and 136 and bell 137 and light 138, wired in parallel therewith. Relay 135 is a delayed timing relay which actuates after an adjustable delay (zero to 10 seconds). Relay 136 closes contacts 143 in the cross red light circuit. Relay 133, having closed contacts 142, the cross circuit amber is energized. Upon the timing relay 135 actuating after the set period of delay, contacts .140 are closed and normally closed contacts 141 are opened, cutting out the cross amber while energizing the cross red. The main control relay 68 in the receiver is a timing relay which is instantaneous in its operation and may be set to open or fall out after any selected period of zero to two minutes. After the timing relay 68 has run its set period, the contacts 71 and 72 open, resulting in deenergization of relay 133. The subsequent opening of all normally open contacts, and closing of all normally closed contacts results in the sequence control means resuming control.

From the foregoing description of the various circuits, it is obvious that several variations of lighting combinations are possible with the instant receiver unit, It is to be appreciated that little or no change to the wiring diagram of existing circuits is necessary in order to accommodate the emergency unit. The emergency unit utilizes its own power supply so as to not interfere with the existing system. It is to be appreciated that a separate power supply is not necessary even though desirable, since the system could be placed across existing lines.

Many beneficial results are forthcoming through the use of such emergency facilities in that emergency vehicles can get to'the scene of the emergency much quicker, and in the areas of crime, fire, rescue, minutes mean the difference between life and death. A further advantage resides in the fact that the chance of of collision between emergency vehicles and autos is lessened. Insurance companies will allow a better insurance rate to the community as a whole because of the reduction in risks and the greater facility of emergency units to get to the scene in a shorter time.

More importantly, the time sequence between the vari-' ous lights is not interrupted nor changed, and upon the passing of the emergency vehicle, the sequence unit takes up in the position it would have been in, notwithstanding the use of separate control by the emergency vehicle. Moreover, the emergency system is separate from the main system so that failure of one system will have no effect on the other system, unless a complete power failure occurs.

The increased activity in AC. transistor design and manufacture for use in switching circuits makes it within the province of this invention to substitute such structure for the various relays shown and described. Therefore, it is intended that the term relay as used herein be taken broadly to include analogous switching circuits incorporating such structure.

While certain illustrative embodiments have been discussed in the foregoing description and disclosed in the appended drawings, it will be immediately apparent to the skilled artisan that a number of modifications could be made to the illustrated embodiment with-out departing from the true spirit of the invention. It is, therefore, my desire to be limited only by the scope of the following claims.

We claim:

1. A remotely controllable signal system comprising, a traffic light having go, caution and stop indicating display means, a first pre-programrned sequencing means periodically permitting actuation of said indicating means in accordance with its pre-programmed sequence, said first pre-programmed sequence means being operatively connected to a first source of power for operation thereof, normally closed switching means operatively connecting said traffic light to said first source of power and permitting actuation of said traffic light indicating means in accor-dance With said first pre-program'med sequencing means, a second pre-programmed sequencing means operatively connected to a second source of operating potential, said second pro-programmed sequencing means being normally in an inoperative condition, signal generating means carried by an emergency vehicle and operative at the command of the vehicle operator to emit a signal of predetermined frequency and characteristics, means responsive to a signal from said signal generating means operatively connected in circuit with said second pre-programmed sequencing means and said switching means,

said responsive means being responsive to said signal generated by said signal generating means to render said switching means to its open state thereby isolating said traffic signal indicating means from said first source of potential, said first pre-programmed sequencing means continuing to operate uninterruptedly during said isolation of said first source of potential from said trafiic signal indicating means, said means responsive concurrently being operative to connect said second pre-programmed sequencing means in circuit with said traffic light indicating means for sequential operation in accordance with the pre-program of said second sequencing means, said traflic light indicating means remaining under the control of said second pre-programmed sequencing means for a pre-established period of time whereupon the traffic signal indicating means will again be controlled by said first preprogrammed sequencing means at the correct point of said first pre-programmed sequencing means, the same as if said signal generated by said emergency vehicle had not occurred.

2. A- remote control traific system comprising, a transmitter carried by an emergency vehicle, said transmitter adapted to transmit a signal of predetermined frequency and characteristics, traffic signal means having go, caution and stop indicating displays, said traffic signal means being selectively positioned at predetermined intersections to control traflic thereat, first pre-programmed sequencing means controlling the timing of said trafiic signal means, a first source of potential, said first pre-programmed sequencing means operatively connected to said first source of potential and generating signals for sequentially activating said indicating displays, normally closed switching means operatively positioned between said first pro-programmed sequencing means said first source of potential and said indicating displays of said trafiic signal, said switching means normally being in a closed position to permit signal transfer therebetween and being responsive to assume an open position preventing actuation signals from said first pre-programmed sequencing means and said first source of potential from reaching said trafiic light indicating displays, said first preprogrammed sequencing means remaining operatively connected to said first source of potential and accordingly continuing to operate during the open position of said switching means, said first pre-programmed sequencing means accordingly being efiective upon reclosure of said normally closed switching means to resume trafiic light control at the proper point of the sequence without interruption or loss of timing sequence occurring, a second pre-programmed sequencing means operatively connected to a second source of operating potential, means responsive for an adjustable predetermined period to detection of a signal from said transmitter for opening said normally closed switching means and for concurrently actuating said second pre-programmed sequencing means, said second pre-programmed sequencing means controlling the timing sequence of said indicating displays for the predetermined period as established by said means whereupon control thereover will revert to said first pre-programmed sequencing means due to reclosure of said normally closed switching means.

3. A remotely controlled signal system comprising, a transmitter carried by an emergency vehicle, said transmitter being operable upon actuation to transmit a signal of predetermined frequency and characteristics, a receiver including a normally unenergized timing relay, said relay being energized in response to receiver detection of a signal from said transmitter, and operating in response to energization to immediately operate its associated contacts, said associated contacts remaining operative for a predeterminedadjustable period, a first source of power, a first pre-programmed sequencing means operatively connected to said first source of power, trafiic signal means having go, caution and stop indicating displays, normally closed switching means operatively connecting said indicating displays to said first source of power in accordance with the sequence of said pre-programmed sequence means, said switching means being operative to open in response to energization of said relay by said receiving means, said switching means operative in its open state to isolate said traffic signal means from actuation by said first pre-programmed sequencing means, said first-preprogrammed sequencing means continuing to operate and generate signals during said open state of said switching means, a second pre-programmed sequencing means operative to generate signals for emergency control of said trafiic light, said second pre-programmed sequence means operatively connected to a second source of power by way of a normally open relay contact, said normally open relay contacts being closed in response to energization of said relay, said second 'pre-programmed sequencing means remaining in control of said traffic light for a predetermined period whereupon said normally opened relay contacts and said normally closed switching means revert to their normal states permitting sequence control of said traffic light by said first pre-programmed sequence means.

4. A remotely controlled signal system comprising, a transmitter carried by a mobile vehicle, said transmitter being operable upon actuation to transmit a signal of predetermined frequency and characteristics, a receiver responsive to detect a signal from said transmitter, a normally unenergized relay operatively connected to said receiver for activation thereby in response to detection of a signal from said transmitter, said relay being operative to keep its associated contacts operative for a predetermined interval of time after activation, a first source of power, a first sequencing means operatively connected to said first source of power, said sequencing means generating signals in accordance with a predetermined desired timing sequence, traffic signal means having go, caution and stop indicating displays, a normally closed switching means operatively connecting said first sequencing means to said trafiic signal means for selectively actuating said indication displays in accordance with said timing sequence, said switching means being operative to open in response to energization of said relay by said receiving means and remaining open for said predetermined interval of said relay, said switching means operative in its open state to isolate said traffic signal means from actuation by said first sequencing means, said first sequencing means continuing to operate without interruption of its timing sequence during said open state of said switching means, a second sequencing means operative to generate signals for emergency control of'said traffic light, normally open relay contacts, said second sequence means operatively connected to a second source of power by way of said normally open relay contacts, said normally open relay contact being closed in response to energization of said relay and remaining closed for a predetermined interval of time as established by said relay, said second sequenching means remaining in control of said traffic light for a predetermined period, as determined by energization period of said relay, whereupon said switching means closes to permit sequence control of said traffic light by said first sequence means at the proper point of the uninterrupted timing sequence thereof.

5. The remote control unit of claim 4 wherein a audible emergency warning signal is operatively connected to said means for emitting an audible signal Warning the traffic at the intersection of the approach of an emergency vehicle.

6. A traffic control system comprising, a first source of power, a plurality of traflic signal means having go, caution and stop indicating displays, a first sequence means operatively connected to said first source of power for energization thereof, normally closed relay contact means operatively connected between said first sequence means and said traflic signal permitting selective predetermined timing operation of said trafiic signal by said first sequence means, said relay contact means preventing operation of said traflic signal by said first sequence means upon actuation into its open state, a second sequence means, a secnd suitable source of power, an emergency Vehicle mounted transmitter generating signals of predetermined frequency and characteristics upon said vehicle approaching a traffic controlled intersection, said signal being generated at the command of the emergency vehicle operator, a receiver including a frequency sensitive filter detecting and responsive to generation of said signals by said transmitter, 22 first normally unenergized relay operatively connected in circuit with said receiver, said relay being energized in response to detection of said transmitter signal by said receiver, first normally open relay'contact means, responsive to energization of said first relay for closure, a second normally unenergized relay having normally open and normally closed relay contacts operatively connected in circuit with said first normally open relay contact means across said second source of potential, said second relay responsive to closure of said first normally open relay contact means for energization thereof, second normally open relay contact in series circuit between said second sequence means and said second suitable source of power, said second relay operative to maintain its associated normally closed relay contact means and said second normally open relay contact in their respective operativestates for an adjustable predetermined period of time, said system permitting control of the indicating displays of said traffic signals according to the control as established by said second sequence means for said adjustable predetermined length of time whereupon the system will revert back to control by said first sequencing means at the proper point in the timing sequence thereof as if an interruption by an emergency vehicle had not occurred.

7. A trafiic control system comprising, a first source of power, a plurality of traflic signal means having go, caution and stop indicating displays, said indicating displays operatively connected across said first source of power, a first sequence means operatively connected across said first source of power for selective energization of said indicating displays in accordance with the timing sequence thereof, a second source of potential, an emergency vehicle mounted transmitter generating signals of predetermined frequency and characteristics upon said vehicle approaching a trafiic controlled intersection, said signal being generated at the command of the emergency vehicle operator, a receiver including a frequency sensitive filter detecting and responsive to generation of said signal by said transmitter, a first normally unenergized relay operatively connected in circuit with said receiver, said relay being energized in response to detection of said transmitted signal by said receiver, a first normally open relay contact closing in response to energization of said first relay, a second relay means operatively connected in series circuit by way of said first normally open relay contact across said second source of potential, said second relay operative upon energization to keep its associated relay contact means in their operative state for a first predetermined adjustable period, a second normally open relay contact meansoperatively connected for response to energization by said second relay, said second relay contacts remaining in their operative state for said adjustable predetermined period as established by said second relay, a third relay means, said third relay operative upon energization to delay operation of its associated relay contact means into their operative states for a second predetermined adjustable period which is substantially less than said first predetermined adjustable period of said second relay said associated contacts thereafter remaining in their operative states during the energization period of said third relay, said third relay having a third normally closed relay contact means associated therewith for operation thereby, and also having a third normally opened relay contact means associated therewith for operation thereby, a fourth relay means, said fourth relay being in a normally unenergized state and having a plurality of normally opened relay contact means associated therewith for operation thereby, a fourth normally closed relay contact means associated with said fourth relay means for operation into its open state upon energization of said fourth relay means, said third and fourth relays being connected in parallel circuit relationship with each other, said parallel connected third and fourth relay means operatively connected in series circuit with said second source of potential by way of said second normally opened relay contact means, said fourth normally closed relay contact mean operatively connected between said indicating displays of said trafiic signal and said first source of potential permitting operation of said indicating means in accordance with said timing sequence of said first sequence means, and prevent-ing operation of said traffic signal by said first sequence means upon actuation thereof into their open state, individual ones of said fourth plurality of normally open contact means in circuit with said stop and caution indicating display means of said trafiic signal, said third normally open relay contact means connecting individual ones of said fourth normally open relay contact and individual stop indicating displays in circuit with aid second source of operating potential said third normally closed relay contact connecting individual ones of said fourth normally open relay contact means and individual ones of said caution indicating displays to said second source of operating potential, such that energization of said first relay means is effective to close its associated normally open relay contact and thereby energize said second normally unenergized relay means for a first predetermined adjustable period, energization of said second relay means being operative to close its associated normally open relay contact means to thereby operatively connect said third and fourth relay means to said second source of potential for operation thereof, energization of said second and third relay means being openative to result in the immediate energization of said fourth relay means to accordingly open the fourth normally closed relay contact means and thereby isolate said first sequence means from said indicating display means of said traffic signal, and to close said plurality of fourth normally open relay contact means, closure of said fourth plurality of normally open contacts resulting in the immediate turning on of said caution indicating display means for a predetermined period of time as established by said second predetermined adjustable period of said third relay means, operation of said associated third normally closed relay contact means and said third normally open relay contact means by said third relay resulting in the assumption of their opposite state by said third relay contacts to thereby accordingly remove the operating potential from said caution indicating display signals and concurrently apply an operating potential to said stop indicating display means for the remainder of the emergency period as determined by the first predetermined adjustable period, whereupon the traffic signal control reverts back to the timing sequence as established by the uninterrupted operating first sequencing means.

8. The trlafi ic control system as defined by claim 7 including an audible emergency indicating signal and flashing light operatively connected across said second source of potential in circuit with said second normally open relay contacts, such that upon closure of said second nor mally open relay contacts an audible and visible warning is given to traffic in the intersection of the approach of an emergency vehicle.

9. A traffic control system comprising, a first source of power, a plurality of traffic signal means having go, caution and stop indicating displays operatively connected across said first source of power, sequence means selectively energizing said indicating displays in accordance with a pre-programmed timing sequence, said sequence means operatively connected across said first source of power for energization thereof, an emergency vehicle mounted transmitter generating signals of predetermined frequency and characteristics upon said vehicle approaching a traffic light controlled intersection, said signal being generated at the command of the emergency vehicle operator, a receiver including a frequency sensitive filter detecting and responsive to generation of said signal by said transmitter, a first normally unenergized relay operatively connected in circuit with said receiver, a first normally open relay contact means associated with said first relay for operation thereby, said first normally open relay contact means operative to close in response to energization of said first relay and remain closed for a first predetermined adjustable period following deenergization of said first relay means, said first relay being energized in response to detection of said transmitter signal by said receiver, a second relay means being normally in an unenergized state, said second relay having second normally open relay contact means and first normally closed contact means associated therewith for operation into their operative state thereby, said secand normally open and first normally closed relay contact means being time-delay responsive to energization of said second relay for a second predetermined adjustable period which is substantially less than said first predetermined adjustable period and thereafter remaining in their operative states for the duration of the energization period of said second relay, a third relay, said third relay being in a normally unenergized state and having a second normally closed relay contact means, and a third plurality of normally open relay contact means, said second normally closed relay contact means and third plurality of normally open relay contacts being responsive to energization by said third relay to assume their opposite states for a period concurrent with the energization of said third relay, said second and third relays each operatively connected in circuit with said second source of potential by way of said first normally open relay contact means, said second normally closed relay contact means operatively connected between said first source of power and said indicating displays of said trafiic signal, individual ones of said third plurality of normally open relay contact means connected in series with individual ones of said caution and stop indicating displays of said traffic signal, said second normally open relay contact means connecting individual ones of said third plurality of normally open relay contacts and individual ones of said stop indicating displays to said second source of potential, said first normally closed contact means connecting individual ones of said third plurality of normally open relay contacts and individual ones of said caution indicating displays to said second source of potential, such that upon energization of said first relay said first normally open relay contact means close to operatively connect said second and third relay means to said second source of potential, operation of said third relay effective to open said second normally closed relay and disconnect said traffic signal indicating means from said first source of potential, but in no way interfering with the timing sequence of said sequence means, said third plurality of normally open relay contact means concurrently closing in response to energization of said third relay to accordingly connect said caution display signals to said second source of potential by way of said first normally closed relay contact means, and thereby energize said caution signals to accordingly alert trafi'ic for a pursuing stop command, said caution display persisting in accordance with the second predetermined adjustable delay of said second relay whereupon said first normally closed relay contact means open to disconnect said caution signal from said second source of potential, said second normally opened relay contacts concurrently closing to operatively connect said stop indicating displays of said trafiic signal to said second source of potential for energization thereof and thereby halt all non-emergency traffic through the intersection, said conditions persisting for a predetermined period as established by said first predetermined adjustable period whereupon said first normally open contacts will revert to their open state and said second normally closed relay contacts revert to their closed state to reconnect said traflic signal display indicators to said first source of potential for selective energization by said sequencing means in accordance with the time sequence thereof.

10. The trailic control system as defined by claim 9 including an audible emergency indicating signal and flashing light operatively connected across said second source of potential in circuit with said second normally open relay contacts, such that upon closure of said second normally open relay contacts an audible and visible warning is given to trafiic in the intersection of the approach of an emergency vehicle.

11. A trafiic control system comprising, a first source of potential, a plurality of traffic signal indicating means having go, caution and stop indicating displays, said indicating means operatively connected to said first source of potential, sequence means selectively energizing said indicating displays in accordance with a pretedermined timing sequence, an emergency vehicle mounted transmitter generating'signals of predetermined frequency and characteristics upon said vehicle approaching a traffic controlled intersection, said signal being generated at the command of the emergency vehicle operator, a receiver including a frequency sensitive filter detecting and responsive to generation of said signal by said transmitter, a second source of potential, a first normally unenergized relay operatively connected in circuit with said receiver, said first relay having a first normally open relay contact means which are closed in response to energization of said first relay, and a first normally closed relay contact means which are opened in response to energization of said first relay, said first normally opened and normally closed relay contact means remaining in their operative states for a first predetermined adjustable period after energization of said first relay, said first relay being energized in response to detection of said transmitter 'signal by said receiver, a second relay means being normally in an unenergized condition and operatively connected in series circuit with said first set of normally opened relay contacts and said second source of potential, said second relay having a second plurality of normally opened relay contact means associated therewith for operation thereby, a third relay means, said third relay operatively connected to said receiver for energization thereby in response to detection of said transmitted signal to delay operation of its associated relay contacts into their operative state for a second adjustable predetermined interval which is substantially less than said first predetermined adjustable period, said associated contacts thereafter remaining in their operative states for the duration of the energization period of said third relay, said third relay having a third normally opened relay contact means associated therewith for operation thereby, a fourth relay means having a fourth plurality of normally opened relay contact means associated therewith for operation thereby, and second normally closed contact means associated therewith for operation thereby, said relay contact means associated with said fourth relay remaining in their opposite states for as long as said fourth relay remains energized, said first normally opened relay contacts operatively connecting said second relay to said second source of potential, said third normally opened contact means operatively connecting said fourth relay to said second source of potential, said first normally closed relay contact means operatively connected in circuit between said first source of potential and said tralfic signal indicating displays, such that said indicating displays will be sequentially turned on in accordance with the timing program established in said sequencing means under non-emergency operating conditions, individual ones of said plurality of normally opened contact means connected in circuit with said caution indicating display means of said trafiic signal, individual ones of said fourth plurality of normally opened relay contact means connected in circuit with individual stop indicating displays,

said first normally closed relay contact means connecting individual ones of said second plurality of normally open relay contact means in circuit with said second source of operating potential one of said second plurality of normally open relay contact means connecting individual ones of said fourth plurality of normally opened relay contact means and individual ones of said stop indicating displays to said second source of operating potential, such that energization of said first relay means is effective to close its associated normally opened relay contact and thereby energize said second normally unenergized relay means and concurrently opening said first normally closed relay contact means to thereby isolate said first sequence means from said indicating display means of said tratffic signal, therewith energization of said second relay to close said second plurality of normally opened relay contact means, closure of said second plurality of normally opened relay contact means resulting in the immediate energization of said caution display signals, energization of said third relay resulting in the closure of said third normally opened relay contact to result in the immediate energization of fourth relay means to thereby result in the opening of its fourth normally closed relay contact means to remove the second source of operating potential from said caution indicating displays and concurrently to close said fourth plurality of normally opened relay contact means, closure of said fourth plurality of normally opened relay contact means resulting in the turning on of said stop indicating display means, said stop indicating display means remaining in an energized condition for the remainder of the emergency period as determined by the first predetermined adjustable period, whereupon the traffic signal control reverts back to the timing sequence as established by the uninterrupted operating first sequencing means.

12. The trafiic control system as defined by claim 11 including an audible emergency indicating signal and flashing light operatively connected across said second source of potential in circuit with said third normally opened relay contacts, such that upon closure of said third normally opened relay contacts an audible and visible warning is given to traffic in the intersection of the approach of an emergency vehicle.

13. A traffic control system for controlling trafiic at traffi'c light controlled intersections under emergency vehicle priority conditions by automatically alerting in line traveling traffi-c,'with the emergency vehicle, of the emergency conditions, while at the same time occasioning a go display, and concurrently therewith changing the cross traffic display indication to caution for a predetermined interval and thereafter to stop for the remainder of the emergency period, the combination comprising, a first source of potential, a plurality of trafiic signal indicating means having go, caution and stop indicating displays, said indicating means operatively connected to said first source of potential, sequence means selectively energizing said indicating displays in accordance with a predetermined timing sequence, said sequence means operatively connected to said first source of operating potential, an emergency vehicle mounted transmitter generating signals of predetermined frequency and characteristics upon said vehicle approaching a trafiic controlled intersection, said signal being generated at the command of the emergency vehicle operator, a receiver including a frequency sensitive filter detecting and responsive to generation of said signal by said transmitter, a second source of potential, a first normally unenergized relay operatively connected in circuit with said receiver, said first relay having a first set of normally opened relay contact means which are closed in response to energization of said first relay, said first set of normally opened relay contact means remaining closed for a first predetermined adjustable period after energization of said first relay, said first relay being energized in response to detection of said transmitter signal by said receiver, a second relay means being normally in an unenergized condition and operatively connected in series circuit with said first set of normally opened relay contacts to said second source of potential for energization, said second relay having a first normally closed relay contact and a second plurality of normally opened relay contact means associated therewith for operation thereby, said first normally closed relay contact operatively connected in circuit between said first source of potential and said tratfic signal indicating displays such that said indicating displays will be operatively connected to said first source of operating potential by way of said first normally closed relay contacts and will be sequentially turned on in accordance with the timing program stored in said sequencing means under non-emergency operating conditions, a third relay means, said third relay operatively connected for delayed operation of its associated contacts for a second predetermined adjustable interval which is substantially less than said first predetermined adjustable interval, said third relay means having a third normally opened relay contact means and a second normally closed relay contact means, said third normally opened relay contact means and said second normally closed relay contact means assuming their operative opposite states an elapsed period of time equal to said second predetermined adjustable period after energization of said third relay means and thereafter remaining in said opposite operating states for the remainder of the energization period of said third relay means, a fourth normally unenergized relay, said fourth relay means having a fourth normally opened relay contact means associated therewith for operation thereby, said fourth normally opened relay contact means assuming a closed condition for so long as said fourth relay remains energized, said third and fourth relays operatively connected in circuit with said second source of potential by way of an individual one of said second plurality of normally opened relay contact means individual ones of said second plurality of normally opened relay contact connected in circuit with the cross traffic indicating caution display of said traflic signal, said cross traffic caution indicating display and said individual one of said second plurality of normally opened relay contact operatively connected to said second source of operating potential by way of said second normally closed relay contact means, said fourth normally opened relay contact connected in circuit with said cross traffic stop indicating display of said trafiic signal, said cross trafiic stop indicating display including said fourth normally opened relay contact operatively connected to said second source of potential by way of said third normally opened relay contact means, said in line go indicating dis-play operatively connected to said second source of potential by said third normally open relay contact means, such that upon energization of said first relay said first set of normally opened relay contacts close to apply energizing potential to said second relay means, energization of said second relay means being operative to open said first normally closed relay contact means to disconnect said traffic signal indicating means from said first source of potential but in no way interrupting the operation or timing sequence of said sequencing means, and concurrently therewith closing said second plurality of normally opened relay contact means to apply energizing potential to said third and fourth relay means, energization of said second relay concurrently resulting in application of said second source of potential to said cross caution indicating display by way of said second normally closed relay contact means and thereby energize said cross caution signal to alert cross traffic to a pursuing stop command, said caution display persisting for said second predetermined adjustable period of time whereupon the normally closed time delay responsive contacts of said third relay open to disconnect said cross caution signal display from said second source of potential, said third normally opened relay contact concurrently closing therewith to operatively connect said go traffic display indicating means in line with the path of travel of the emergency to be operatively connected to said second source of potential for energization thereof and also concurrently connecting said cross stop indicating display of said traffic signal to said source of potential for energization thereof and thereby halting all cross trafiic through the intersection, said conditions persisting for said first predetermined adjustable period of time whereupon said first normally closed relay contacts will revert to their closed state to reconnect said traffic signal display indicators to said first source of potential upon reapplication of said first source of potential to said indicating display means said display means thereafter being capable of selective energization by said sequencing means at the proper timing point thereof the same as if an emergency condition had not occurred.

14. The trafiic control system as defined by claim 13 including an audible emergency indicating signal and flashing light operatively connected across said second source of potential in circuit with said first normally opened relay contact, such-that upon closure of said first normally opened relay contact an audible and visible warning is given to trafiic in the intersection of the approach of an emergency vehicle.

References Cited by the Examiner UNITED STATES PATENTS 4/1959 Cook et al. 34033 9/1959 Schwab 34033 

1. A REMOTELY CONTROLLABLE SIGNAL SYSTEM COMPRISING, A TRAFFICE LIGHT HAVING GO, CAUTIN AND STOP INDICATING DISPLAY MEANS, A FIRST PRE-PROGRAMMED SEQUENCING MEANS PERIODICALLY PERMITTING ACTUATION OF SAID INDICATING MEANS IN ACCORDANCE WITH ITS PRE-PROGRAMMED SEQUENCE, SAID FIRST PRE-PROGRAMMED SEQUENCE MEANS BEING OPERATIVELY CONNECTED TO A FIRST SOURCE OF POWER FOR OPERATION THEREOF, NORMALLY CLOSED SWITCHING MEANS OPERATIVELY CONNECTING SAID TRAFFIC LIGHT OF SAID FIRST SOURCE OF POWER AND PERMITTION ACTUATION OF SAID TRAFFICE LIGHT INDICATING MEANS IN ACCORDANCE WITH SAID FIRST PRE-PROGRAMMED SEQUENCING MEANS, A SECOND PRE-PROGRAMMED SEQUENCING MEANS OPERATIVELY CONNECTED TO A SECOND SOURCE OF OPERATING POTENTIAL, SAID SECOND PRE-PROGRAMMED SEQUENCING MEANS BEING NORMALLY IN AN INOPERATIVE CONDITION, SIGNAL GENERATING MEANS CARRIED BY AN EMERGENCY VEHICLE AND OPERATIVE AT THE COMMAND OF THE VEHICLE OPERATOR TO EMIT A SIGNAL OF PREDETERMINED FREQUENCY AND CHARACTERISTICS, MEANS RESPONSIVE TO A SIGNAL FROM SAID SIGNAL GENERATING MEANS OPERATIVELY CONNECTED IN CIRCUIT WITH SAID SECOND PRE-PROGRAMMED SEQUENCING MEANS AND SAID SWITCHING MEANS, SAID RESPONSIVE MEANS BEING RESPONSIVE TO SAID SIGNAL GENERATED BY SAID SIGNAL GNERATING MEANS TO RENDER SAID SWITCHING MEANS TO ITS OPEN STATE THEREBY ISOLATING SAID TRAFFIC SIGNAL INDICATING MEANS FROM SAID FIRST SOURCE OF POTENTIAL, SAID FIRST PRE-PROGRAMMED SEQUENCING MEANS CONTINUING TO OPERATE UNINTERRUPTEDLY DURIGN SAID ISOLATION OF SAID FIRST SOURCE OF POTENTIAL FROM SAID TRAFFICE SIGNAL INDICATING MEANS, SAID MEANS RESPONSIVE CONCURRENTLY BEING OPERATIVE TO CONNECT SAID SECOND PRE-PROGRAMMED SEQUENCING MEANS IN CIRCUIT WITH SAID TRAFFIC LIGHT INDICATING MEANS FOR SEQEUNTIAL OPERATION IN ACCORDANCE WITH THE PRE-PROGRAM OF SAID SECOND SEQUENCING MEANS SAID TRAFFIC LIGHT INDICATING MEANS REMAINING UNDER THE CONTROL OF SAID SECOND PRE-PROGRAMMED SEQUENCING MEANS FOR A PRE-ESTABLISHED PERIOD OF TIME WHEREUPON THE TRAFFIC SIGNAL INDICATING MEANS WILL AGAIN THE CONTROLLED BY SAID FIRST PREPROGRAMMED SEQUENCING MEANS AT THE CORRECT POINT OF SAID FIRST PRE-PROGRAMMED SEQUENCING MEANS, THE SAME AS IF SAID SIGNAL GENERATED BY SAID EMERGENCY VEHICLE HAD NOT OCCURRED. 